Electric resistance coils free from induction and capacity



Sept. 8, 1925. I 1,552 686 P. EVEIRSHEIM ELECTRIC RESISTANCE COILS FREEFROM INDUCTION AND CAPACITY FilBd 3 1924 Patented 19 25.

UNITED I-STIATES/ PATENT OFFICE-.-

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ELECTRIC RESISTiNCE COCIILS FREE FROM INDUCTION AND CAPACITY.

Application filed January 3, 1924. Serial Io. 884,284.

To all whom it may concern:

Be it known that, I, PAUL EvnRsHnIM, residing at Bonn-on-the-Rhine, inthe State of Prussia, Germany, have invented certain 5 new and usefulImprovements in Electric Resistance Coils Free from Induction andCapacity, of which thefollowing is a specification.

Electrical resistance coils free from ca- 1 pacity are in themselvesknown. They are usually characterized by the wire windings beingarranged so that the separate windings cross. This construction is onlyapplicable for relatively fine wires, and only then if it is possible towind the windings on asolid core.

According to the invention resistance coils free from induction andcapacity can be manufacturedby winding two like coils formed of aconductor of any required cross section, the one right handed and theother left handed, radially inserted in one another,

to alternate the rings of the respective coils, and connected so thatadjacent coils are 2 traversed by currents in opposite directions. Theinvention works most efiiciently by the use of a material in ribbon orband form which in known manner is wound on edge. Such edge wound coils"are in themselves known, but could not formerly be wound as resistancesfree from induction and ca-.

pacity. According to the invention the re quired object is effected in avery simple manner by clamping means introduced into the core of thecoils inserted in one another, the clamping means being a pliedexternally against the sharp edges 0 the bands and thereby holding thecoils in their position. -An example of a construction according 4 tothe invention is shown in the accompanying drawing, in which Fig. 1 is afront view of a coil and Fig. 2 a plan of the winding scheme of thecoils.

The whole coil consists oftwo separate 4 helical coils 8 and 8,, which,as indicated by the arrows, are wound in opposite directions. Thewinding of the se arate coils is efiected in known manner an the woundcoils are then, as shown in Fig.' 1, laterally inserted in one anotherin the radial direction so that the separate coils will alternate witheach other. A hollow core f remains in the centre between the coils. Inthis core clamping means are introduced, for example bestos. 'of, theedge wound strips and so maintain curved strips 0 of asbestos, which arepressed by means of sheet metal strips 6, also curved, and, a rod epressed against the inner edges of the coils. .The coils are also heldtogether by -means of strips 9, also made of insulating material,inserted between the inner and outer circumference of the two coils inthe intermediate space h.

The insulating strips a and g are pre erably made of an elasticmaterial, for example as- They penetrate into the sharp edges thewindings rigidly in position.

The two coils are inserted in one another so that the windings aresubstantially enclosed one by the other. If a current F is introducedbymeans of an arc shaped conductor 0, current traverses the coil 8, to theleft and the coil 8, to the right. By this arran ement self-induction isexcluded as in a i-filar winding. The new arrangement has, however, theadvanta' e as compared to a bi-filar winding that t e capacity isexceedingly small, practically zero, for the following reasons:

' It is known that the charge of a condenser is dependent on the valueof the potential between the coatings. If this is very small,

the char e also must be correspondingly small. mce in the present casethe two coils are connected to ether in parallel, between two windings tere can only be the small potential difierence due to the fall ofpgten'tialin' one winding. There is also the rther advantage that etweenthe se arate layers-of resistance only a very smal layer of insulationis required in order to, prevent the assage of the current from onewinding to t e other. In one very simple construction, the usuallyformed external skin of oxide is suflicient.

The invention, therefore, enables resist ances free from induction andcapacity to be constructed which have, moreover, the

ascertained the nature of my said invention and inwhat manner the sameis to be performed, I declare that what I claim is 1. An electricresistance free from induc- 'tion and capacity, consisting of coils ofthe same dimensions to offer the same resistance, wound the one rightand'the other left, made of a conductor of any required cross section,the coils being inserted in one another to overlap the rings of thecoils and connected in multiple are so that neighbouring windings aretraversed by currents in opposite directions.

2. In the structure recited in claim 1, an

insulator su port extending through all the rings of hot coils.

3. An electric resistance, free from induction and capacity according toclaim 1, in which the two coils consist of a ribbon or band materialwound edgewise in known manner.

In testimony whereof I aifix my signature.

DR. PAUL EVERSHEIM.

